Relevance of knight shift measurements to the electronic density of states

The Knight shift, $\mathcal{K}$, measures the magnetic hyperfine field at the nucleus produced by the conduction electrons which are polarized in a magnetic field. Knight shifts are often dominated by the Pauli term and, in its most simple form, can be written as $\mathcal{K}=\langle a\rangle {\chi }_p$. Here χ_p is the conduction electron Pauli spin susceptibility which depends on the density of states at the Fermi level, N(E_f), and ⟨a⟩ is an average magnetic hyperfine coupling constant associated with the wave function character at the nucleus, ∣ψ_F(0)∣², for conduction electrons at the Fermi surface.